Roadmap of Microelectronic Industry

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Roadmap of Microelectronic Industry
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Scaling of MOSFET
Reduction of channel length L ? L/a
Integration density ? a2 Speed ? a
Power/device ? 1/a2 Power density unchanged
Voltage ? 1/a Equivalent thickness of gate
oxide ? 1/?
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Gate Dielectric film in ULSI MOSFET
Gate oxide
Gate
n
n
p-Si
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Equivalent Gate Oxide ThicknesstEq tx
?SiO2/?x ?x dielectric constant of insulator
X ?SiO2 3.2 Use high-?x insulator
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Possible epitaxial dielectric films on Si
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Metallization target parameters
(current)
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Electromigration Effects
Void Pile-up
Electron wind and field-driven atomic migration
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Multi-level Metallization
RC delay issue
Lower levels fine connections to individual
devices Upper levels thicker/wider common
connections Cu metallization reducing wire
resistance Low-k dielectrics reducing parasitic
capacitance
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Lithography shorter wavelength (deep UV, X-ray,
electron/ion beams) source, optics, resist
materials
Gate insulator with high dielectric constant
(high-k), high dielectric strength, effective
barrier to impurity (e.g., B) migration
Si-on-insulator (SOI) reducing capacitive
coupling between devices, power consumption,
effective heat dissipation
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Double-gate FET
Double-gate FET by selective epitaxial growth
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Single-electron Tunneling (SET)
Transistor Coulomb blockade effect
Devices based on quantum effects in
nano-structured materials quantum dots/wire,
nano-wires (e.g., carbon nanotubes), molecular
devices,
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Index of Single-wall Carbon Nanotubes (SWNT)
Armchair (n, n)   Zigzag (n, 0) General (m, n)
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Electronic properties of SWNTs
SWNTs 1D crystal If m - n 3q ? metallic
Otherwise ? semiconductor
Zigzag, dt 1.6nm
?18?, dt 1.7nm
Bandgap of semiconducting SWNTs
?21?, dt 1.5nm
?11?, dt 1.8nm
Armchair, dt 1.4nm
1.42 Å, ? 5.4 eV, overlap integral
STM I-V spectroscopy
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Doping of semiconductor SWNTs N, K atoms ?
n-type B atoms, oxygen ? p-type
SWNT Transistors
SWNT CMOS inverter its characteristics
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Molecular diodes and nonlinear devicesMolecule
with D-?-A structure C16H33Q-3CNQ
D
?
A
Highly conductive zwitterionic D-?-A- state at
1-2V forward bias Reverse conduction state
D--?-A requires bias of 9V I-V curve of Al/4-ML
C16H33Q-3CNQ LB film/Al structure
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Ultimate Physical Limits
Thermodynamic limit energy consumption in
handling 1 bit of information kT log 2 ? 18 meV
3 ? 10-21 J at RT Current products Pentium
4, power consumption 30 W, consists gt 2.5 ? 106
devices operating at gt 4 ? 108 Hz, energy cost
per bit of operation ? 10-15 J Demonstrated in
laboratory energy cost of operating a
single-molecule switch is 10-19 J
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Real Materials and their Processing

• Particles, lines and rigid bodies vs. real
  materials each material has its own
  characteristics
• Material-specific properties determine the
  function and processing details of a material
• Comprehensive knowledge of materials processing
  requires 5-10 years of learning and practice
  Interdisciplinary between physics, chemistry,
  electronics, materials science, economics
• Advantage and role of physicist

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Graduate Attributes (Southern Cross University,
Australia)

• Intellectual rigour
• Creativity
• Ethical understanding, sensitivity, commitment
• Command an area of knowledge
• Lifelong learning --- ability of independent
  self-directed learning
• Effective communication and social skills
• Cultural awareness
• (From S. Yeo, CDTLink, NUS, July 2004)

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Final Exam

• 24 Nov, two hours
• One A4 cheat sheet allowed, both sides
• What will be in the exam?
• Basic principle, processes, mainly after
  Chapter 5